Experimental investigation of specific energy and wear intensity of diamond-impregnated core bits in rock drilling

Drilling is one of the most important and expensive geological survey processes. The wear of drill bits is closely related to the specific energy that expresses the energy consumption of the drilling process and significantly affects the total cost of drilling. In this article, the correlation between the wear intensity and the specific energy was examined. For the purpose of obtaining the necessary information, a series of experiments were performed on a horizontal laboratory drilling rig with the use of 8 types of rocks and 5 diamond-impregnated small-diameter core drill bits with synthetic diamonds of various qualities. The selected drilling mode was the mode with a constant rotation speed and an increasing thrust force. Results of the experimental measurements indicated that relatively high rotation speeds were preferred for the tested drill bits for the purpose of efficient drilling. The lowest amount of the specific energy required for drilling was observed for sandstone and andesite, i.e. the rocks in which radial cracks were formed around the chipped-off crater during the drilling. A simple linear regression between the intensity of wear of the drill bits and the specific energy was found. The evaluation of the results of this experimental research also showed that the quality of the used diamonds significantly affected the wear intensity.